We are using Excel driver 4.0 dated in 2020 and found that XLS files keep assigned by the driver for as long as our program is running.
If we use .xlsx files this problem do not occur using the exact same driver properties.
I know that our maintenance is expired and we plan to renew it but I would like to know if this particular problem is already solved.
Try delayedClose=0 connection property.
Rememember to close connection, if your jdbc url contains .xls file name.